The Effect of Illegal Immigration and Border Enforcement on Crime Rates along the U.S.-Mexico Border (Working Paper #131)

Abstract: In the 1990s, the border led the nation in the decline of property-related crimes, while violent crime rates fell twice as fast in the U.S. than in the median border county. This paper asks how changes in illegal immigration and border enforcement have played a role in generating these divergent trends. We find that while migrant apprehensions are correlated with a greater incidence of violent crime, they are not systematically associated with higher rates of property crime. Border patrol enforcement is associated with lower property crime rates but higher violent crime. Interestingly, it is local enforcement (same or neighboring sector) that is correlated with higher violent crime. Higher border enforcement overall is correlated with less violent crime. Several trends likely underlie these results. First, more enforcement in urban versus rural areas has pushed property crime rates down by keeping migrants and smugglers away from densely populated areas. Second, it is likely that more enforcement (and other factors) have led to an increased use of professional smugglers which in turn has led to more violence on the border.